A nucleotide sequence of PERP (hereinafter also referred to as THW or PIGPC1) has been already known (Patent references 1 to 13) and a polypeptide encoded by the PERP gene is presumed to be a protein comprising 193 amino acids and a 4-transmembrane protein from its primary sequence. It has been known that the polypeptide encoded by PERP gene is a protein related to p53-dependent apoptosis (Non-patent reference 1). It has been also shown that, in thymus cells and nerve cells prepared from PERP gene knockout mice, apoptosis induction upon damage of DNA is partially inhibited (Non-patent reference 2). It has been also reported that PERP is a gene which lowers its expression in highly metastatic cancer cells (Non-patent reference 3).
As an antibody binding to a polypeptide encoded by the PERP gene (hereinafter referred to as “anti-PERP antibody”), a polyclonal antibody prepared from an intracellular partial peptide in the C terminal or a partial peptide of the first extracellular loop in a PERP gene product as an immunogen has been known (Non-patent references 4 and 5). These polyclonal antibodies have been shown to be applicable to Western blotting or immunohistostaining. Up to now, no antibody which recognizes the three-dimensional structure of an extracellular region of polypeptide encoded by PERP gene and binds to the extracellular region has been known.
It has been known that, when an antibody of non-human animals such as a mouse antibody is administered to human, it is usually recognized as a xenobiotic substance and accordingly, a human antibody against a mouse antibody (human anti-mouse antibody: HAMA) is induced in human body. It has been known that HAMA reacts with the administered mouse antibody to induce side effects (Non-patent references 6 to 9), promotes the disappearance of the mouse antibody from the body (Non-patent references 7, 10 and 11) and reduces the therapeutic effect of the mouse antibody (Non-patent references 12 and 13).
In order to solve these problems, it has been attempted to prepare a humanized antibody such as a human chimeric antibody or a humanized antibody from an antibody of non-human animals by using genetic recombination techniques.
In comparison with an antibody of non-human animals such as a mouse antibody, the human chimeric antibody or the humanized antibody has various advantages in clinical application to human. It has been reported, for example, that, in experiments using monkeys, immunogenicity of the human chimeric antibody or the humanized is lowered and its half-life period in blood becomes longer in comparison with a mouse antibody (Non-patent references 14 and 15). Thus it is expected that, in comparison with the antibody of non-human animals, the human chimeric antibody or the humanized antibody has little side effects in human and its therapeutic effect lasts for a long period.
In addition, since the human chimeric antibody or the humanized antibody is prepared by using genetic recombination techniques, it can be prepared as molecules in various forms. For example, when the γ1 subclass is used as a heavy chain (hereinafter referred to as “H chain”) constant region (hereinafter referred to as “C region”) (H chain C region will be referred to as “CH”) of a human antibody, it is possible to prepare a human chimeric antibody and a humanized antibody having a high effector function such as antibody-dependent cellular cytotoxicity (hereinafter referred to as “ADCC”) (Non-patent reference 14) and prolonged half-life in blood can be expected in comparison with a mouse antibody (Non-patent reference 15). Particularly, in the treatment where expressed cell numbers of polypeptide encoded by the PERP gene are decreased, high cytotoxic activity such as complement-dependent cytotoxic activity (hereinafter referred to as “CDC activity”) and ADCC activity via Fc region of an antibody (region which is in the downstream of a hinge region of the antibody H chain) is important to the therapeutic effect and, therefore, the human chimeric antibody and the humanized antibody is preferred in comparison with the antibody of non-human animals such as a mouse antibody (Non-patent references 16 and 17).
Moreover, as a result of the progress in protein engineering and genetic engineering in recent years, the human chimeric antibody or the humanized antibody can also be prepared as antibody fragment having a low molecular weight such as Fab, Fab′, F(ab′)2, a single chain antibody (hereinafter referred to as “scFv”) (Non-patent reference 18), a dimerized V region fragment (hereinafter be referred to as “diabody”) (Non-patent reference 19), a disulfide stabilized V region fragment (hereinafter referred to as “dsFv”) (Non-patent reference 20), a peptide comprising CDR (Non-patent reference 21) and the like, and these antibody fragments are better in transition to target tissues than whole antibody molecules (Non-patent reference 22).
The above-described facts show that, as an antibody to be used for clinical application to human, a human chimeric antibody, a humanized antibody or the antibody fragment thereof is preferred than an antibody of non-human animals such as a mouse antibody. Many proteins, including antibodies, existing in living organisms are modified by sugar chains. Sugar chains are classified into an N-linked sugar chain which specifically binds to an asparagine residue and an O-linked sugar chain which binds to a serine residue and a threonine residue. Particularly, in sugar proteins having an N-linked sugar chain, a consensus sequence (asparagine-any amino acid-serine or threonine) comprising three amino acid residues to which the sugar chain binds is present (Non-patent reference 23). However, it is not always true that an N-linked sugar chain binds to all consensus sequences. For example, in two consensus sequences of N-linked sugar chain in human TNF-α receptor II of maturation type, 100% N-linked sugar chain is bound in one of them while, in the other, N-linked sugar chain is bound in a possibility of as low as about 50% (Non-patent reference 24). The same phenomenon is also confirmed in bovine DNase I and, further, when a host cell for the production of genetic recombinant product changes, a pattern of sugar chain binding greatly changes and, even in the same amino acid sequence, addition of sugar chain is not constant depending upon the environment for protein expression (Non-patent reference 25).
Usually, a constant region of human antibody of IgG type has one consensus sequence of N-linked sugar chain. However, in an antibody having a consensus sequence of an N-linked sugar chain even in its variable region, binding of sugar chain changes and it becomes difficult to stably provide an antibody which is uniform as a pharmaceutical. Furthermore, there are some cases where sugar chain is essential for binding of proteins. For example, it has been reported that, in LFA-3 (lymphocyte function-associated antigen 3), an N-linked sugar chain is necessary for binding of LFA-3 to CD2 and there is a possibility that, when a sugar chain is bound to a variable region which is a binding site of an antibody, the binding activity of the antibody to the antigen is changed (Non-patent reference 26).    (Patent reference 1) WO98/55508    (Patent reference 2) WO99/54461    (Patent reference 3) WO00/55350    (Patent reference 4) WO01/22920    (Patent reference 5) WO01/66719    (Patent reference 6) WO00/61612    (Patent reference 7) WO02/00174    (Patent reference 8) WO02/47534    (Patent reference 9) US2003-0064947    (Patent reference 10) US2003-0065157    (Patent reference 11) WO00/55629    (Patent reference 12) WO02/60317    (Patent reference 13) US2002-0119463    (Non-patent reference 1) Genes & Development, 14, 704 (2000)    (Non-patent reference 2) Curr. Biol., 13, 1985 (2003)    (Non-patent reference 3) Anticancer Research, 20, 2801 (2000)    (Non-patent reference 4) Home page of Pro Sci Incorporated, on line, retrieved on Mar. 31, 2004, internet <www.prosci-inc.com/Antibody-TDS/2451%20PERP.html>    (Non-patent reference 5) Home page of Novus Biologicals, Inc., on line, retrieved on Mar. 31, 2004, internet <www.novus-biologicals.com/print_data_sheet.php/4400>)    (Non-patent reference 6) J. Clin. Oncol., 2, 881 (1984)    (Non-patent reference 7) Blood, 65, 1349 (1985)    (Non-patent reference 8) J. Natl. Cancer Inst., 80, 932 (1988)    (Non-patent reference 9) Proc. Natl. Acad. Sci. USA, 82, 1242 (1985)    (Non-patent reference 10) J. Nucl. Med., 26, 1011 (1985)    (Non-patent reference 11) J. Natl. Cancer Inst., 80, 937 (1988)    (Non-patent reference 12) J. Immunol., 135, 1530 (1985)    (Non-patent reference 13) Cancer Res., 46, 6489 (1986)    (Non-patent reference 14) Cancer Res., 56, 1118 (1996)    (Non-patent reference 15) Immunol., 85, 668 (1995)    (Non-patent reference 16) J. Immunol., 144, 1382 (1990)    (Non-patent reference 17) Nature, 322, 323 (1988)    (Non-patent reference 18) Science, 242, 423 (1988)    (Non-patent reference 19) Nature Biotechnol., 15, 629 (1997)    (Non-patent reference 20) Molecular Immunol., 32, 249 (1995)    (Non-patent reference 21) J. Biol. Chem., 271, 2966 (1996)    (Non-patent reference 22) Cancer Res., 52, 3402 (1992)    (Non-patent reference 23) Biochem. J., 195, 639 (1981)    (Non-patent reference 24) Biochemistry, 32, 3131 (1993)    (Non-patent reference 25) Biochem. J., 355, 245 (2001)    (Non-patent reference 26) Trends in Glycoscience and Glycotechnology, 11, 1 (1991)